The present invention is related to treated glass fibers and, more particularly, to an elastomeric coating composition for treating glass fibers that yields coated glass fibers having improved weaveability. Glass fibers constitute continuous glass fibers as well as strands, yarns, cords, and fabrics formed thereof. Glass fibers have been used in various ways in woven products, such as, those in the carpet industry.
The use of glass fiber strand in woven products requires that the glass fibers have a soft protective coating to protect the glass fibers in the strand from interfilament abrasion and to provide characteristics such as lack of brittleness needed in the production of the woven product. The coated glass fiber strand must have sufficient weaveability to allow its use in woven products.
Weaveability is a characteristic that glass fiber strand must have to undergo satisfactorily the weaving process, where the strand is wound around a cop inside a shuttle of a weaving loom. The process involves transporting the shuttle, or the strand itself in a shuttleless loom, back and forth across the loom so the strand unravels from the cop to supply the weft in between the warp strands running perpindicular to the weft strands. As the strand unravels, it is coiled to some degree due to its previously wound condition. The coiled strand is vulnerable to breakage from the force applied to it in being transported across the loom. To avoid breakage from this force the strand should have a good knot tensile strength. The knot tensile strength as measured by American Society of Testing Materials (ASTM) Standard D-2256 measures the tensile strength of the strand when folded over itself in a knot. Generally glass fiber strand composed of glass fibers having small diameters have better weaveability than strands composed of coarser glass fibers. The problem with this is that strands composed of fine glass fibers are more expensive to produce.
Coated glass fiber strand composed of glass fibers having a large diameters and possessing good weaveability would be useful in many woven products. For example in the past the fill material for woven carpets that is used as the weft to lock in the pile and other components was composed of jute fibers. Jute fibers made good carpet fill material, since the fibers are quite strong and reasonably stable. Recently the availability of jute has become a problem. This coupled with the recognized problem of lack of uniformity of jute fibers has led to the replacement of jute with glass fibers as carpet fill material. The glass fibers used to replace the jute have been in the form of waste tire cord or glass fiber strand composed of small diameter glass fibers. Coated glass fiber strand is an excellent replacement for jute in carpet fill material because of the uniformity, dimensional and heat stability and strength of the glass fiber present therein. The replacement of jute by glass fiber strand requires a coated glass fiber strand with good weaveability and one that is not too tacky. This is obtained when the glass fibers in the strand have a small diameter, i.e. G-fiber diameter or smaller. In "The Manufacturing Technology of Continuous Glass Fibers," K. L. Lowenstein, Elsevir Scientific Publishing Company, New York, 1973 at page 26, there is an explanation of the filament diameter and strand designation by letter, which is hereby incorporated by reference. The economic penalty incurred in using strands with small diameter glass fibers must be tolerated, since strands with glass fibers of larger diameters lack good weaveability to make a good carpet fill material or other woven products. Waste tire cord is not readily used in producing woven products because the cord is too tacky and involves additional process steps to reduce the tackiness.
Also, it is well known in the art that plasticizers or softeners can be used in a material to increase the material's susceptibility to plastic flow, flexibility, workability, and distensibility. But it is also well known in the art, that the incorporation of a plasticizer into a material decreases the strength of the material and in some cases when plasticizers are added to materials render them tacky.
It is an object of the present invention to provide coated, coarser, glass fibers that possess sufficient strength, stability and lack of brittleness, and adequate knot tensile strength characteristics without being too tacky to produce coated glass fiber strands with improved weaveability.
It is an additional object of the present invention to provide a coating composition to coat glass fibers to increase the glass fibers strength, stability, lack of brittleness, and weaveability and knot tensile strength without an adverse increase in tackiness to permit the glass fibers to be produced in coarser, more economic filaments that are made into strands for use in woven products.